1. Field of the Invention
This invention relates to refrigeration or heat pump apparatus containing stable wear-inhibiting working fluid consisting essentially of a refrigerant and a chemically inert wax-free lubricant. More particularly, the invention concerns such apparatus and working fluids in which the refrigerant is a halo-substituted hydrocarbon and the lubricant contains the combination of higher fatty acid and arylphosphate to improve wear-inhibiting properties and to improve resistance to decomposition.
2. Prior Art
Mineral lubricating oils have been developed containing the combination of triarylphosphate such as tricresylphosphate and higher fatty acids such as oleic acid in order to improve lubricating properties. See, for instance, U.S. Pat. Nos. 2,241,531, 2,431,008 and 2,730,499.
Refrigeration apparatus and working fluids in such apparatus have been developed in which mineral lubricating oil is used as lubricant and various additives such as ethylene diamine tetraacetic acid, or a salt thereof and nitrous oxide are used to inhibit chemical instability of the oil-refrigerant mixture. See, for instance, U.S. Pat. Nos. 3,532,631 and 3,812,040, the former of which also notes that tricresylphosphate additive accelerates oil-refrigerant reaction.
Refrigeration apparatus and working fluids in such apparatus have also been developed in which synthetic alkylbenzene lubricating oil is used as lubricant, but it appears that wear-inhibiting and stabilizing additives for such fluids have not been suggested. See, for instance, U.S. Pat. Nos. 3,092,981, 3,169,928 and 3,642,634, as well as French Patent No. 1,413,765.